MERRILL] METEOR CRATER OF CANYON DIABLO, ARIZONA 477 



sand. A part of this was nickel-bearing, as noted in the record given 

 of the borings, and in some instances, notably holes No. 16 and 20 

 (Fig. 125), carried metallic particles. The presence of this nickel- 

 bearing sand was naturally of great significance, and attempts were 

 made to isolate the nickeliferous mineral in order to ascertain its pos- 

 sible meteoric character. The white sand showed numerous slag-like 

 granules, which, in the section, were found to be composed of sand 

 grains cemented by iron oxides, and larger granules (y 2 mm.) of a 

 greenish color, the nickel reaction being limited to the latter. Exam- 

 ined under the microscope, these proved to be aggregates of fine 

 angular bits of the quartz sand, stained by a greenish, amorphous 

 material, concerning the true nature of which the microscope re- 

 vealed nothing. 



Hole No. 17 yielded at a depth of 520 feet abundant sand grains 

 stained brown-red by iron oxides and commingled with it occasional 

 minute — perhaps 1 mm. in diameter — thin metallic scales, which it 

 was at first thought might have come from the drill, but which Mr. 

 Tassin's tests showed to consist of phosphide of iron and to be un- 

 questionably schreibersite and of meteoric origin. Small scales of 

 nickel-iron were also found, 1 and in one instance (hole No. 16) a 

 number of chromite and fayalite ( ?) granules. The source of these 

 last is conjectural, since neither mineral has thus far been identified 

 in the meteoric iron, though Derby gives a trace of chromium in 

 the analysis noted later. Careful search was made for anything in 

 the nature of a silico-ferruginuous slag, such as it was conceived 

 might result from the mutual fusion of sand grains and meteoric 

 iron. Nothing was found that could be thus positively identified 

 until hole No. 20 was reached, though some of the particles showed 

 in thin-section a very deep green or brownish, blebby glass which 

 it was at first thought might be particles of the volcanic sand common 

 to the region. A comparison of the two materials did not substantiate 

 this view, and it would seem that such must be in some way con- 

 nected with the meteoric phenomena, though it was not possible to 

 correlate them absolutely with the nickeliferous granules. Hole No. 

 20 yielded a quantity of dark brownish particles from I to 3 mm. in 

 diameter, which in thin sections showed a ground of radiating, im- 

 perfectly differentiated crystals of a gray color and undetermined 



'Analyses by Mr. Tassin of the metallic particles, freed from siliceous matter 

 as much as possible by hand picking and the magnet, yielded : Si0 2 , 12.75 

 per cent; Fe, 68.17 per cent; NiCo, 12.14 P er cent; P, 5.07 per cent; total, 

 08.93 per cent. The Si0 2 was in form of free quartz. 



